Methods for removing particles from etching chamber

ABSTRACT

A method includes forming a coating layer in a dry etching chamber, placing a wafer into the dry etching chamber, etching a metal-containing layer of the wafer, and moving the wafer out of the dry etching chamber. After the wafer is moved out of the dry etching chamber, the coating layer is removed.

BACKGROUND

The formation of integrated circuit often involves etching metal layers.For example, aluminum-containing gate electrodes and aluminum copperpads are commonly seen integrated circuit components. These componentsare formed by depositing a blanket metal layer, and then patterning theblanket metal layer as desirable patterns using an etching process.

The etching of the metal layer may be performed in a dry etchingchamber, which is vacuumed, and etching gases are introduced into theetching chamber to etch the metal layer. In the etching process, plasmais generated from the etching gases. The metal ions in the metal layermay sometimes react with the ions in the etching gases to formparticles. For example, when aluminum is etched, the aluminum ions mayreact with fluorine ions to form aluminum fluorine (AlF) particles,which stick to the inner surface of the etching chamber. The bonding ofthe AlF particles to the inner surface of the etching chamber, however,is weak. Hence, the bonds between the AlF particles and the innersurface may break, and the AlF particles fall on wafers, causingmanufacturing yield to drop.

AlF has a high vaporizing temperature. Hence, it is difficult to removethe AlF particles.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a process flow in accordance with some embodiments;

FIG. 2 illustrates a cross-sectional view of a dry etching tool inaccordance with some embodiments;

FIG. 3 illustrates a perspective view of a gas-flow re-distributormounted in a dry etching chamber in accordance with some embodiments;and

FIGS. 4 through 8 illustrate the cross-sectional views of intermediatestages in the etching of a metal layer in a wafer in accordance withsome embodiments, wherein a coating layer is formed and removed.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the invention. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to be limiting. For example, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed between the first and second features, such thatthe first and second features may not be in direct contact. In addition,the present disclosure may repeat reference numerals and/or letters inthe various examples. This repetition is for the purpose of simplicityand clarity and does not in itself dictate a relationship between thevarious embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

A dry etching process and the corresponding particle removal process areprovided in accordance with various exemplary embodiments. Theintermediate stages of performing the dry etching and theparticle-removal and metal clean processes are illustrated. Theapparatus for the dry etching and removing the particles is alsoillustrated. The variations of the embodiments are discussed. Throughoutthe various views and illustrative embodiments, like reference numbersare used to designate like elements.

FIG. 1 illustrates process flow 100 for etching a wafer in a dry etchingchamber, the corresponding process for forming and removing a coatinglayer, and a metal cleaning process in accordance with some embodiments.The process flow as shown in FIG. 1 is also discussed in detailreferring to the process steps shown in FIGS. 4 through 8. A briefdiscussion is provided as follows. First, a coating layer is depositedin an etching chamber of a production tool (step 102). The coating layermay be deposited in the locations over a wafer station, on which a waferis to be disposed in a subsequent step. The wafer is then etched (step104), during which the undesirable metal particles may be generated. Thecoating layer includes the material that can bond with the metalparticles formed in subsequent steps. Accordingly, the coating layeracts as a glue layer for “adhering” the metal particles, so that it isdifficult for the metal particles to fall on the wafer, and hence themanufacturing yield is improved. The coating layer is then removed (step106) from the chamber, and the metal particles are also removed from thechamber along with the coating layer. Next, a gas-flow redistributor isalso cleaned to remove the metal particles thereon. Steps 102 through108 may be repeated for the etching of each of wafers.

FIG. 2 illustrates a cross-sectional view of etching tool 10, whichincludes etching chamber 12. Etching tool 10 is configured to be usedfor dry etching processes, in which gases rather than wet etchingsolutions are used for etching wafers. Etching chamber 12 is configuredto be vacuumed, for example, through pump 14, through which the airand/or process gases in etching chamber 12 are evacuated. Wafer station16 is located in chamber 12. In some embodiments, wafer station 16 is anelectrical Chuck (E-Chuck), which is configured to secure a waferthereon through an electrical force.

Gas-flow re-distributor 18 is mounted in chamber 12 to separate chamber12 into a top portion over gas-flow re-distributor 18, and a bottomportion under gas-flow re-distributor 18. Gas-flow re-distributor 18 isused to force the gas overlying wafer station 16 to flow through thethrough-holes 20 in gas-flow re-distributor 18, so that the distributionof the gas flow is more uniform. For example, gas-flow re-distributor 18may include a plurality of through-holes 20 aligned to a plurality ofconcentric rings (also refer to FIG. 3). The concentric rings havecenter 22, which is also the center of wafer station 16. Thethrough-holes (such as 20-1, 20-2, 20-3, 20-4, or 20-5) aligned to thesame concentric ring may have the same size (area) and/or the sameshape. Furthermore, the through-holes (such as 20-1) aligned to theinner concentric rings that are closer to the center 22 have diameterssmaller than the through-holes (such as 20-5) aligned to the outerconcentric rings that are farther away from the center 22. In someexemplary embodiments, with the increase in the distance betweenthrough-holes 20 and center 22, the sizes (areas) of the respectivethrough-holes 20 increase gradually. Alternatively stated, thethrough-holes 20 aligned to each of the outer concentric rings may havesizes greater than the through-holes 20 that are aligned thethrough-holes 20 that are aligned to respective inner concentric rings.

In some embodiments, through-holes 20 are aligned to five (or more orfewer) concentric rings, with the corresponding through-holes 20 denotedas 20-1, 20-2, 20-3, 20-4, and 20-5, with 20-1 being the innermostthrough-holes, and 20-5 being the outmost through-holes. Through-holes20 may have round top-view shapes, for example, as illustrated in FIG.3. Alternatively, through-holes 20 may have any other top-view shapessuch as polygon shapes. In some exemplary embodiments, through-holes20-1 have a diameter in the range between about 5 mm and about 10 mm,through-holes 20-2 have a diameter in the range between about 10 mm andabout 13 mm, through-holes 20-3 have a diameter in the range betweenabout 13 mm and about 15 mm, through-holes 20-4 have a diameter in therange between about 15 mm and about 18 mm, and through-holes 20-5 have adiameter in the range between about 18 mm and about 20 mm. It isappreciated, however, that the values recited throughout the descriptionare merely examples, and may be changed to different values.

With the inner through-holes 20 having smaller sizes than the outerthrough-holes 20, the gas flow resistance for process gas or air flowingthrough the inner through-holes is greater than the gas flow resistancefor the process gas or air flowing through the outer through-holes.Since pump 14 is aligned to center 22, the gas/air in the region overwafer station 16 tends to flow through the paths closer to wafer station16 faster. Therefore, by increasing the gas flow resistance of the innerpaths closer to wafer station 16, more gas/air is diverted to flowthrough the outer paths farther away from wafer station 16. By selectingappropriate sizes for through-holes, as described in the embodiments ofthe present disclose, the gas/air flow is substantially uniform, and theback-stream of the gas/air, which back-stream flows upwardly in certainregions, is eliminated. Since the back-stream may cause more metalparticles that are generated by the etching of wafers (as shown in FIG.6) to fall on wafers, eliminating the back-stream may improve the yieldof wafers.

As shown in FIG. 3, gas-flow re-distributor 18 has a ring shape (in thetop view) with inner edge 18A and outer edge 18B. The body of gas-flowre-distributor 18 is between inner edge 18A and outer edge 18B. Bothinner edge 18A and outer edge 18B form concentric rings. The inner edge18A defines opening 24 (FIG. 2) therein, with wafer station 16 residingin opening 24. As shown in FIG. 2, in some embodiments, opening 24 hasradius R1, which may be in the range between about 140 mm and about 160mm. The radius R2 of the outer edge of gas-flow re-distributor 18 may bein the range between about 280 mm and about 330 mm. The distance betweenthe inner edge and the outer edge may be in the range between about 140mm and about 170 mm. Gas-flow re-distributor 18 may include anodizedaluminum as a base material, with Y₂O₃ coated on the surfaces of thebase material. The thickness of gas-flow re-distributor 18 may be in therange between about 5 mm and about 15 mm.

FIG. 3 illustrates a perspective view of wafer station 16 and gas-flowre-distributor 18 in accordance with some embodiments, wherein inneredge 18A and the outer edge 18B of gas-flow re-distributor 18 aremarked. Through-holes 20 are located between inner edge 18A and outeredge 18B. The size difference between some of through-holes 20 are alsoschematically illustrated in FIG. 3. Gas-flow re-distributor 18 may beelectrically grounded. It is appreciated that the sizes of through-holes20 are schematic, and the optimum sizes of through-holes 20 may bedifferent from what is shown.

FIGS. 4 through 8 illustrate a production cycle in accordance with someembodiments of the present disclosure. Referring to FIG. 4, coatinglayer 30 is deposited on the inner surface of chamber 12. The respectivestep is shown as step 102 in process flow 100 of FIG. 1. Coating layer30 is also deposited in the region over wafer station 16 and gas-flowre-distributor 18, and not in the region underlying wafer station 16 andgas-flow re-distributor 18. In some embodiments, coating layer 30comprises a silicon-based material, which may be a silicon-based oxide.For example, coating layer 30 may include SiClO_(x) and/or SiO_(x),wherein x is the number of oxygen atoms in the respective molecule.Value x may be 3 or 4 for SiClO_(x), or 1 or 2 for SiO_(x).

When coating layer 30 is to comprise SiClO_(x), with x being 3 or 4, therespective process gases used for forming coating layer 30 may includeSiCl₄ and oxygen (O₂). Argon may or may not be included. SiCl₄ andoxygen react to form SiClO_(x), wherein more oxygen results in moreSiClO₄ and less SiClO₃, and vice versa. On the other hand, 2hen coatinglayer 30 is to comprise SiO_(x), wherein x may be 1 or 2, the respectiveprocess gases may include SiH₄ and oxygen (O₂), and argon may or may notbe included. SiH₄ and oxygen react to form SiO_(x), wherein more oxygenresults in more SiO₂ and less SiO, and vice versa.

In the process for forming coating layer 30, the process gases areintroduced into chamber 12, and are in-situ reacted. In some exemplarycoating process, the pressure of the processes is in the range betweenabout 10 mTorr and about 30 mTorr, which is considered as a highpressure because in similar deposition processes, a pressure higher thanabout 5 mTorr is typically considered as a high pressure. The power forthe reaction may be in the range between about 500 Watts and about 1,500Watts. The flow rate of argon may be in the range between about 10 sccmand about 50 sccm. The flow rate of SiCl₄ may be in the range betweenabout 100 sccm and about 300 sccm. The flow rate of O₂ may be in therange between about 50 sccm and about 100 sccm. The reaction time may bein the range between about 10 seconds and about 20 seconds. Thickness T1of the coating layer 30 on the top inner surface and the top parts ofthe sidewalls may be in the range between about 5 Å and about 50 Å.

The “high” pressure used in the coating process will reduce the meanfree path and prolong gas residence time of the reaction gas, so thatthe radicals of the reaction gases may survive longer. As a result,coating layer 30 is mainly deposited on the upper portions (of theregion over wafer station 16) of the inner surface of chamber 12, whilein the lower portions (of the region over wafer station 16), thethickness of coating layer 30 is small. There may be a transitionregion, as illustrated, in which the thickness of coating layer 30reduces gradually. The transition region may occur, for example, atapproximately the same level as wafer 32 (FIG. 5). This may ensure thatat the level higher than wafer 32, the thickness of coating layer 32 isadequate to cover the upper portion of the inner surface of chamber 12without leaving any portion uncovered. Since the metal particles adheredto the lower portions (of inner surface of chamber 12) that are lowerthan wafer 32 are not able to fall on wafer 32, the quality and thecoverage of coating layer 30 in the lower portions of the etchingchamber do not adversely affect the effect of coating layer 30. Coatinglayer 30 may or may not be deposited on gas-flow re-distributor 18 sinceits position is low. The coating layer 30 on gas-flow re-distributor 18,if any, may be very thin.

FIG. 5 illustrates the etching of wafer 32 in etching tool 10. Therespective step is shown as step 104 in the process flow 100 of FIG. 1.Wafer 32 is placed on, and is secured on, wafer station 16. A dryetching process is performed on surface layer 34 of wafer 32. Surfacelayer 34 is a metal-containing layer comprising a metal such as aluminum(Al), aluminum copper (AlCu), TaAlC, TiAlC, or the like, which is analuminum-containing metal layer in accordance with some embodiments.Surface layer 34 may be any metal layer that is used in the integratedcircuit manufacturing processes. For example, the metal layer mayinclude, and is not limited to, metal gates, metal contact plugs, ametallization layer in low-k dielectric layers, aluminum copper metalpads over the top metallization layer, post passivationinterconnections, under-bump metallurgies, metal pads, and so on. Inalternative embodiments, metal-containing layer 34 may also bealuminum-free. The etching gas is thus chosen according to the materialof metal-containing layer 34. In some exemplary embodiments, thepressure of the etching gas (such as Cl₂, BCl₃, and/or oxygen (O₂)) isin the range between about 1 mTorr and about 5 mTorr. The power for theetching may be in the range between about 300 Watts and about 1,000Watts, with the voltage of the power source being in the range betweenabout 50 volts and about 200 volts. The flow rate of Cl₂ may be in therange between about 30 sccm and about 100 sccm. The flow rate of BCl₃may be in the range between about 20 sccm and about 50 sccm. The flowrate of O₂ may be in the range between about 2 sccm and about 10 sccm.

In the etching process, the residue metal ions of metal-containing layer34, such as Al ions, may remain in chamber 12, which may be caused bythe sputtering resulted from the plasma used in the metal etchingprocess. In a subsequent process, an in-situ metal cleaning may beperformed, for example, using a fluorine-containing gas (such as SF₆) asa cleaning gas for removing the residue ions. In the exemplary metalcleaning process, SF₆ is introduced into chamber 12. The fluorine ionsreact with the metal ions such as Al ions to generate metal particles.The metal particles, such as aluminum fluoride (AlF) particles, areattached to coating layer 30, as illustrated in FIG. 5. Thesilicon-containing coating layer 30 includes positively charged siliconions, which bond with the negatively charged fluorine ions in AlF togenerate Si—F bonds. Fluorine ions are further bonded to the aluminumions. Accordingly, through the Si—F bonds, the AlF particles are adheredto coating layer 30. An advantageously feature of the embodiments of thepresent disclosure is that the Si—F bonds are strong bonds, which do notbreak easily. Accordingly, it is unlikely that the AlF particles willfall on wafer 32. As a comparison, although the inner surface materialof the chamber 12 may sometimes contain quartz, which includes silicon,the silicon atoms in quartz have weak bonds to the F ions in AlF,wherein the weak bonds may easily break. Accordingly, the AlF particlesmay fall on the wafers in chamber 12 if coating layer 30 is not formed.

In some embodiments, the AlF particles may also be adhered to gas-flowre-distributor 18, which is illustrated as 36 in FIG. 5. The Y (yttrium)atoms in gas-flow re-distributor 18 also have the function of bonding tothe AlF particles. It is appreciated that the bonding between the AlFparticles and gas-flow re-distributor 18 may not be as strong as thebonding between the AlF particles and coating layer 30. However, sincethe position of gas-flow re-distributor 18 is lower than wafer 32, anyfallen metal particles will be evacuated by pump 14 without being ableto fall on wafer 32. Accordingly, the metal particles on gas-flowre-distributor 18 will not be able to affect the manufacturing yield.

Wafer 32 is then moved out of chamber 12, and the resulting etching tool10 is illustrated in FIG. 6. The resulting chamber 12 includes the AlFparticles on coating layer 30 and gas-flow re-distributor 18.

Coating layer 30 is then removed in an in-situ etching step, and theresulting etching tool 10 is shown in FIG. 7. The respective step isshown as step 106 in the process flow 100 of FIG. 1. Advantageously, theAlF particles attached on coating layer 30 are removed along with theremoval of coating layer 30. The coating removal may be performed usingetching gas such as NF₃ or other process gases that may be used to etchcoating layer 30, depending on the material of coating layer 30. Whencoating layer 30 comprises materials other than silicon-based oxides,different process gases may be used. Argon may or may not be added. Insome exemplary embodiments, the pressure of the etching gas (such asNF₃) is in the range between about 100 mTorr and about 300 mTorr. Thepower for the etching may be in the range between about 800 Watts andabout 1,500 Watts. The flow rate of NF₃ may be in the range betweenabout 500 sccm and about 1,000 sccm. The flow rate of argon may be inthe range between about 50 sccm and about 100 sccm.

After the coating removal step as shown in FIG. 7, coating layer 30 isremoved along with the AlF particles attached thereon. The removedcoating layer 30 and the metal particles are evacuated through pump 14.On the other hand, metal particles such as AlF particles 36 may stillremain on gas-flow re-distributor 18, partly because coating layer 30may not be formed on gas-flow re-distributor 18, and hence the removalof coating layer 30 does not result in the removal of AlF particles 36.An additional in-situ metal cleaning process is then performed to removeAlF particles 36. The respective step is illustrated as step 108 in theprocess flow 100 FIG. 1.

Referring to FIG. 8, in the metal cleaning process, the process gasesthat can be used to remove metal particles 36 are introduced intochamber 12. For example, when metal particles 36 are AlF particles,chlorine (Cl₂) and/or BCl₃ gases may be used. Cl₂ and BCl₃ may be usedtogether to achieve better results. In some exemplary embodiments, thepressure of the etching gas (such as Cl₂ and BCl₃) is in the rangebetween about 1 mTorr and about 5 mTorr. The power for the etching maybe in the range between about 300 Watts and about 800 Watts. The flowrate of Cl₂ may be in the range between about 50 sccm and about 200sccm. The flow rate of BCl₃ may be in the range between about 30 sccmand about 100 sccm. The flow rate of argon may be in the range betweenabout 10 sccm and about 100 sccm. In some embodiments, etching tool 10includes different coils (not shown) encircling different parts ofchamber 12, such as the top part, the middle part, and the bottom part.Accordingly, the setting of the coils (such as the current flowingthrough the coils) may be adjusted, so that the coils encirclinggas-flow re-distributor 18 may be provided with a higher current thanother coils, and hence the efficiency of the metal cleaning is improved.

In some embodiments of the present disclosure, coating layer 30 isremoved before the metal cleaning step. In alternative embodiments, themetal cleaning step is performed before the removal of coating layer 30.

As a result of the metal clean, metal particles 36 are substantiallyfully removed from chamber 12, and hence the yield of the subsequentprocess steps will not be affected by the metal particles generated inthe cycle shown in FIGS. 4 through 8. Next, referring back to theprocess flow in FIG. 1, the process loops back to step 102 to etch asubsequent wafer, and the steps 102, 104, 106, and 108 are performedagain. The respective process steps are also shown in FIGS. 4 through 8.The cycles may be repeated for a plurality of wafers. In the embodimentsof the present disclosure, the etching of each of the wafers isaccompanied by the formation and the removal of a coating layer and ametal cleaning of the gas-flow re-distributor. In alternativeembodiments, the etching of two wafers, three wafers, or a greaternumber of wafers is accompanied by the formation and the removal of acoating layer.

The embodiments of the present disclosure have some advantageousfeatures. By forming a coating layer, and then removing the coatinglayer after the metal etching process, the undesirable metal particlesmay be adhered tightly to the coating layer, so that the metal particleswill not fall on the wafer. The metal particles are removed by removingthe coating layer. By forming the coating layer using a relatively highpressure, the top part of the chamber is covered more thoroughly withthe coating layer. Since the yield loss is mainly affected to the metalparticles falling from the top part of the chamber, the problem offalling particles is eliminated effectively.

In accordance with some embodiments of the present disclosure, methodincludes forming a coating layer in a dry etching chamber, placing awafer into the dry etching chamber, etching a metal-containing layer ofthe wafer, and moving the wafer out of the dry etching chamber. Afterthe wafer is moved out of the dry etching chamber, the coating layer isremoved.

In accordance with alternative embodiments of the present disclosure, amethod includes placing a wafer into a dry etching chamber, with agas-flow re-distributor located in the dry etching chamber. The gas-flowre-distributor includes an inner edge encircling a wafer station, withthe wafer being placed on the wafer station, an outer edge concentricwith the inner edge, and a plurality of through-holes between the inneredge and the outer edge. A metal-containing layer of the wafer isetched. The wafer is then moved out of the dry etching chamber. Afterthe wafer is moved out of the dry etching chamber, an in-situ etchingprocess is performed to remove metal particles from a surface of thegas-flow re-distributor.

In accordance with yet alternative embodiments of the presentdisclosure, an apparatus includes a dry etching chamber, a wafer stationin the dry etching chamber; and a gas-flow re-distributor located in thedry etching chamber. The gas-flow re-distributor separates the chamberinto a top portion over the gas-flow re-distributor and a bottom portionunder the gas-flow re-distributor. The gas-flow re-distributor includesan inner edge encircling the wafer station, an outer edge concentricwith the inner edge, and a plurality of through-holes between the inneredge and the outer edge. The plurality of through-holes connects the topportion of the dry etching chamber to the bottom portion of the dryetching chamber.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method comprising: forming a coating layer in adry etching chamber; placing a wafer into the dry etching chamber;etching a metal-containing layer of the wafer; moving the wafer out ofthe dry etching chamber; and after the wafer is moved out of the dryetching chamber, removing the coating layer.
 2. The method of claim 1,wherein between the forming the coating layer and the removing thecoating layer, a single wafer is etched.
 3. The method of claim 1,wherein the forming the coating layer comprises forming a SiClO_(x)layer, with x being three or four.
 4. The method of claim 1, wherein theforming the coating layer comprises forming a silicon oxide layercomprising SiO or SiO₂.
 5. The method of claim 1, wherein when theforming the coating layer and the etching the metal-containing layer ofthe wafer are performed, a gas-flow re-distributor is located in the dryetching chamber, with the gas-flow re-distributor comprising: an inneredge encircling a wafer station, wherein the wafer is placed on thewafer station; an outer edge concentric with the inner edge; and aplurality of through-holes between the inner edge and the outer edge. 6.The method of claim 5 further comprising performing an in-situ etchingprocess to remove metal particles on a surface of the gas-flowre-distributor.
 7. The method of claim 1, wherein the coating layer isdeposited on upper parts of an inner surface of the dry etching chamber,and not is deposited on lower parts of the inner surface of the dryetching chamber.
 8. The method of claim 1, wherein the forming thecoating layer is performed at a chamber pressure in a range betweenabout 10 mTorr and about 30 mTorr.
 9. A method comprising: placing awafer into a dry etching chamber, with a gas-flow re-distributor locatedin the dry etching chamber, wherein the gas-flow re-distributorcomprises: an inner edge encircling a wafer station, wherein the waferis placed on the wafer station; an outer edge concentric with the inneredge; and a plurality of through-holes between the inner edge and theouter edge; etching a metal-containing layer of the wafer; moving thewafer out of the dry etching chamber; and after the wafer is moved outof the dry etching chamber, performing an in-situ etching process toremove metal particles from a surface of the gas-flow re-distributor.10. The method of claim 9, wherein the in-situ etching process comprisesetching aluminum fluoride particles from the surface the gas-flowre-distributor.
 11. The method of claim 9, wherein the etching themetal-containing layer of the wafer comprises etching analuminum-containing layer of the wafer.
 12. The method of claim 9further comprising: before the placing the wafer into the dry etchingchamber, forming a coating layer in a dry etching chamber; and after thewafer is moved out of the dry etching chamber, removing the coatinglayer.
 13. The method of claim 12, wherein the placing the wafer, theetching the metal-containing layer, the moving the wafer, the in-situetching process, and the removing the coating layer are performed ineach of a plurality of cycles, wherein in each of the plurality ofcycles, a single wafer is etched.
 14. The method of claim 12, whereinthe forming the coating layer comprises forming a silicon-based oxidelayer.
 15. A method comprising: conducting a first process gas into aprocess chamber, wherein a wafer station is resided in the processchamber; reacting the first process gas to deposit a coating layer on aninner sidewall of the process chamber; placing a wafer into the processchamber having the coating layer; performing a dry etch on the wafer;retrieving the wafer out of the process chamber; and conducting a secondprocess gas into the process chamber to remove the coating layer. 16.The method of claim 15, wherein the first process gas comprises asilicon-containing gas.
 17. The method of claim 15, wherein the reactingthe first process gas to deposit the coating layer is performed when thewafer station is resided in the process chamber.
 18. The method of claim15, wherein the coating layer is formed on sidewalls of an upper portionof the process chamber, and is not formed on sidewalls of a lowerportion of the process chamber.
 19. The method of claim 15, wherein thedry etch on the wafer comprises etching an aluminum-containing layer ofthe wafer.
 20. The method of claim 15, wherein between the depositingthe coating layer and the removing the coating layer, a single wafer isetched.